Dealing with Chlorine and Chloramine in Water

Many of you were wondering how to deal with chlorine and chloramine in your water. I’ve started using an inline hose water filter—a type of Brita filter on steroids. Here’s a link to some recommended ones. Pay attention to the expected “gallons-filtered life.”

Inline Hose Filter Reviews

One drop of humic acid per gallon of water will also neutralize the chlorine. Ascorbic acid (vitamin C) will neutralize them both. Please note, humic acid products vary by the percent of humic acid they contain. The first one I bought contained 3%. Ian Hunter mentioned Humax in one of the soil science podcasts and it is at 12%. The one Dr. Ingham sells on her Environment Celebration website is 5%. If you don’t want to order humic acid off the web, check your local hydroponics store (AKA pot grower’s supplier) if you can’t find it at a local nursery, which you probably won’t. The hydroponics store may also carry an inline filter.

If you want to listen to the soil food web god herself, Dr. Elaine Ingham, talk about water quality and the humic acid trick, here’s a link to a podcast where she talks about them. She also talks about how plants and the microbes interact. Informative listening. Unfortunately, she doesn’t talk about the concentration of humic acid she is referring to.

No-Till Market Garden Podcast: Dr. Elaine Ingham

If you don’t want to listen to it via the web, then search for No Till Elaine Ingham on your podcast app. It’s episode 21.

Enjoy a glass of water that contains a lemon or cucumber slice while you listen. It’ll then be chlorine and chloramine free. (The slice isn’t really needed though because your stomach acids do the neutralization.)

Here’s some other links on the subject:

Vitamin C and Chloramine

Vitamin C and Chlorine


De-chlorinating additives are also widely available for ponds and aquariums. Letting the water sit for 24-48 hours with a decent size air stone also removes the chlorine.

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@el_cheezer Letting water sit may remove cholines, but in the UK at least it’s to my understanding that they use chloramines these days, over chlorine. Contrary to what’s true with chlorine evaporating off in 24-48 hours, chloramines won’t and in fact leaving it to stand and evaporate I’ve heard would ultimately concentrate it. De-chlorinating additives you mentioned for pond or aquarium would take care of either though.

@Ace :+1:t2: I will give the podcast a listen and thanks for the info on inline hose filters. I didn’t know such thing existed – will have to do some research into UK/European equivalents!


Any idea how the humic and/or ascorbic acid would interact with the phosphoric acid I use to bring the pH of my water down from 8 to around 6.5? The pH of my solution for the injector is about 5 which is a fairly dilute solution.

I’m not a chemist, but in this study they used humic acid and phosphoric acid together.

Test the two together on tree or two to be safe.

Mixing phosphoric acid and bleach causes chlorine gas to be emitted, but drinking water is treated with phosphoric acid as an anticorrosive for the pipes. Because the amounts of chlorine and phosphoric acid are so small the reaction between the two must not be an issue in drinking water. Perhaps a chemist out there can shed light on the issue.

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Passing your water through a good quality carbon filter will take care of the chlorine’s

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I think there is some confusion around the what chlorine and acids are.

First, chlorine is a oxidizing agent. When chlorine, Cl2, reacts with something you get the reduced form of Chlorine, Cl- or chloride. When you add something to a solution containing chlorine to “neutralize” it you are conducting this reaction.

Chloroamine, NH2Cl, used in drinking water is longer lived than chlorine, but serves the same purpose, it is an oxidizing agent. when given something to oxidize chloroamine is converted to NH4+(ammonium) and Cl-, chloride.

The reactions of Humic acid and Ascorbic acid with chlorine and chloroamine have nothing to do with the fact that they are acids. The reactions are oxidation/reduction chemistry and should not affect pH. Ascorbic acid is a commonly used reducing agent in chemical synthesis. It is basically a sacrificial compound.

As far as lowering the pH of water, the best option is likely using vinegar, or acetic acid, Using phosphoric acid will likely make iron less available to your trees.

Just in case anyone wants to know, I am a chemist.


Good work, thanks for the research!

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Could you explain why the use of phosphoric acid would prevent the uptake of iron please? I used citric acid once and it really made the water smell awful. I did however adjust a whole barrel 40 gallons and with in two days it was cloudy and stinking. I use phosphoric acid pretty much all the time and have had no problems, I do though use a trace element fruit once a year.

Sure thing. For Iron to be available to the plant it need to be soluble and in solution. When Phosphoric acid, H3PO4, is in solution there are actually multiple forms of phosphate present, H2PO4^-, HPO4^2-, and PO4^3-. The ratio of these species present will depend on pH. Phosphate has a very high affinity for soluble free iron, Fe^3+. When phosphates and Fe^3+ are in solution together they will form the insoluble mineral FePO4, iron phosphate. Most fertilizer manufacturers get around this problem by introducing a chelating agent, usually EDTA, to prevent iron from coming out of solution.

I bet your trace element treatment contains iron and other metals in their chelated forms which keeps them available to the plant.

If you use an unchelated iron source then phosphate containing water will likely precipitate it. This is why phosphates are used to limit the corrosion of iron pipes. Phosphates prevent iron from dissolving.

Hope this helps


Perfect. Thank you so much. Your correct the trace element frit/not fruit. Does contain chelated iron. I did use a pholyphosphate filter for a while and I did notice an iron deficiency. We have a ph of around 7.4 amd a TDS of 240 I’m seriously considering just changing over to a RO unit and mixing the water back to what I need. Thank you for your help.

Here’s how Michael Hagedorn at Crataegus Bonsai uses a hose siphon and muriatic acid to adjust the pH in his water.

Adjusting soil pH


Good point on the phosphoric acid binding to dissolved iron. I have not noticed any yellowing due to lack of iron. I picked phosphoric since it would yield a slight fertilizer aspect and was the most common in the hydroponics store. I mix a 5 gallon batch and syphon into the hose for about a week. I considered both vinegar and muratic acid, but thought the acetic acid might evaporate out and did not like the idea of adding more Cl- to the water. I also thought about nitric since a small amount of nitrate would also fertilize, but it is a strong acid a far more dangerous to handle than phosphoric.



Acetic acid can evaporate overtime, but if are adding acid to neutralize basic water then the acid is not in its free acidic form and thus will not easily evaporate. Say you have calcium carbonate (CaCO3) in your water and it is basic. If you neutralize CaCO3 with acetic acid (CH3COOH) you will get the following reaction.

CaCO3 + 2CH3COOH --> Ca^2+ 2CHCOO^- + H2O + CO2

The acetic acid (CH3COOH) gets converted to its acetate form (CH3COO^-) which will not evaporate.

I would not worry about adding chloride to the water. At the concentrations you would be using it to simply adjust pH, Cl- will not be detrimental.

As far as acid strength is concerned there is a lot of confusion about what “strong acid” means. Strong acid means that when you add the acid to water it breaks up into its component ions completely. Nitric acid (HNO3) is completely converted to H^+ and NO3^-. Muriatic acid, AKA Hydrochloric, (HCl) is also completely converted to its ions H^+ and Cl-. Both HNO3 and HCl are strong acids.

Phosphoric and Acetic Acids are weak acids, meaning they do not completely break up into their ions in solutions, Phosphoric becomes a mixture of H3PO4, H2PO4^- and H^+, and acetic becomes a mixture of CH3COOH, CH3COO^- and H^+.

Phosphoric acid and Nitric acid are both dangerous when concentrated. All acids, when concentrated can cause burns. Strength simply refers to the amount of acid you need to add to a solution to see a corresponding change in pH. You will need to add more phosphoric acid than nitric acid to a solution to get an eqaul change in pH.

In my opinion, everyone worried about their water quality should simply catch rain water and use it to water their bonsai. That’s my plan anyway. I live in the mountains where the water be very alkaline.

Hope this helps.


75 gallon per day RO unit. I have no idea why I procrastinated so long. Half RO water to half of my un chlorinated mains water. PH 6.5 TDS 110.

@Ace and @Ch3mnerd thank you for sharing all this information. :heart_eyes: This is a great thread! Instead of posting a new topic, what I was going to ask is relevant enough to this thread.

I’ve read what’s been said here and if I understand correctly dosing an acid can neutralise the chloramines and buffer the pH down to fix my quite lime-laden tap water in Southeast England. Dosing the acid is an option.

However, as I’d like to use rainwater where possible and “top-up” the water butt (which I pump out of for my watering), it’s more straightforward and convenient for me to use an RO unit (plus I already have one) to top up the butt. In the driest summer months, this may mean more “filling up” the butt than “topping up”.

My query is specifically around RO vs the acid-treated tap water (pretty hard water in my area):

  • RO will remove the chloramines.
  • RO, like distillation, will remove the vast majority of dissolved solids including the lime and trace minerals.
  • Rainwater strikes me as being a kind of large-scale distillation and so rainwater to fairly pure and deficient of trace minerals(?) I can’t imagine it would pick these up in any noticeable extent from the atmosphere on the way back down.
  • Conversely, rainwater having run through miles of rock etc. can pick up the trace minerals (including lime, if in limestone areas). But short of using well well water for our trees the most viable option for many may be an occasional additive of Trace Elements for plants, or a fertiliser which has these micronutrients in addition to the macronutrients.

In short, I was wondering if there are any negative implications of using RO filtered water due to lack of trace minerals?

If 100% RO is simpler for me, would I need to remineralise it or mix with half chloramine treated tap water as @Nicknjh23 is to reintroduce the trace minerals present in tap water?

Would acid-treated tap water be significantly preferable to RO, or vise-versa?

RO water will strip the water of pretty much everything, you will need to re mineralise. By adding your tap water that has stood for a couple of days or been filtered through charcoal you can re mineralise the RO water. You would encounter all sorts of problems using pure RO water. RO water usually comes out at between PH 5-6. So maybe to acid. It’s also very unstable and the Ph can drop significantly. You will need to invest in a Ph and a TDS meter. Start by adding Half to half and see what readings you get. So where about dim the south east are you. I used to live in Ashford kent. Something else to remember. Making Ro water is quite wasteful. If I can help anymore please ask.

Hi Nick, thanks for the reply. I’m in Southeast London.

Regarding tap water that has stood for a couple of days. Bear in mind my comment from earlier in this thread.

Letting water sit may remove cholines, but in the UK at least it’s to my understanding that they use chloramines these days, over chlorine. Contrary to what’s true with chlorine evaporating off in 24-48 hours, chloramines won’t and in fact leaving it to stand and evaporate I’ve heard would ultimately concentrate it. De-chlorinating additives you mentioned for pond or aquarium would take care of either though.

I have a TDS and pH meter. I keep planted aquariums and the points you mention about pure RO are familiar and relevant for that. For example, using RO in a tank where wood (tannins), fish waste, detritus and most of all Co2 (if diffusing co2 for the plants) can swing the pH of the unstable RO. But in a dark, inert water butt, which factors are there that can affect the pH to mean it’s problematic for watering our trees?

Also, what sort of problems did you mean? A little more details if possible. And how are the same problems not also a problem for rainwater? :thinking:

The Kh hardness of water keeps it stable, the lower this is the more liable water is to swing. I used to keep Discus tropical fish many years ago. All I know is that if I didn’t re mineralise the RO water and just store it the Ph would tumble. I have used the method described above many times in the past with no problems. If there is nothing in the RO water. Then trace elements aren’t available to the plants. All I can say is having water at ph 6.5 amd a TDS of around 100-120 will be perfectly acceptable for Bonsai cultivation. I’m sure others on this thread can answer your other questions in more detail.

Sure, I don’t doubt it for keeping a fish tank! But it’s a different application and the water’s being kept/stored in different circumstances as mentioned above.

Again, I suspect rainwater is very low in these too (?), not as much as RO perhaps, but still cause for occasional additive or use of ferts with micronutrients.

If a lower TDS is acceptable too, then that’s much simpler in my case. Cheers anyway for the input :+1:t2: